Wind models and ionizing fluxes of massive stars at very low metallicity

Wind Models of massive stars with metallicities in a range from 0.0001 to 1.0 solar are calculated using a new treatment of radiation driven winds with depth dependent radiative force multipliers and a comprehensive list of more than two millions of spectral lines in NLTE. The calculations yield mass-loss rates, wind momenta and wind energies as a function of metallicity and can be used to discuss the impact of stellar winds on the evolution of stellar populations in the early phases of galaxy formation. Ionizing fluxes of hot stars depend crucially on the strengths of their stellar winds, which modify the absorption edges of hydrogen and helium (neutral and ionized) in the far UV. The new wind models are therefore also used to predict ionixing fluxes of massive stars as a function of metallicity.